I was reading about the early wagons and wagon trains which shaped America’s Western expansion and ran onto an interesting tidbit: Habits of early freighters and their freight wagons, such as the huge Conestoga wagons, are responsible for American traffic traveling along the right side of the road.
According to William Foster-Harris’ wonderful book I’ve cited frequently, early pioneers and freighters did not ride in or on their wagons most of the time to drive their horses. The early pioneers at least loaded the wagons and walked alongside them. They used the wagon space and the horses’ strength to carry stuff, not people.
But, Foster-Harris indicates, when they were weary, they either jumped onto the back of one of the wagon horses to rest their feet, or they rode on a “lazy board” as it was called. This, Foster-Harris said, was “a stout oak plank that pulled out from the left side of the huge Conestoga freight wagon.”
You can figure out the rest, I’m sure. If the travelers were hopping up and down from a plank extending from the left side of the Conestoga, the custom eventually would demand wagons stay to the right, so they could make sure about clearance on the left side of the wagon — to prevent damage and injuries to the freight and freighters.
So blame it on the Conestoga.